4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IMA Integrity measurement architecture is enabled.
48 IOSCHED More than one I/O scheduler is enabled.
49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support is enabled.
53 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are enabled.
93 FTRACE Function tracing enabled.
94 TS Appropriate touchscreen support is enabled.
95 UMS USB Mass Storage support is enabled.
96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
103 X86-32 X86-32, aka i386 architecture is enabled.
104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
106 Documentation/x86/x86_64/boot-options.txt .
107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
109 In addition, the following text indicates that the option:
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
115 Parameters denoted with BOOT are actually interpreted by the boot
116 loader, and have no meaning to the kernel directly.
117 Do not modify the syntax of boot loader parameters without extreme
118 need or coordination with <Documentation/x86/boot.txt>.
120 There are also arch-specific kernel-parameters not documented here.
121 See for example <Documentation/x86/x86_64/boot-options.txt>.
123 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124 a trailing = on the name of any parameter states that that parameter will
125 be entered as an environment variable, whereas its absence indicates that
126 it will appear as a kernel argument readable via /proc/cmdline by programs
127 running once the system is up.
129 The number of kernel parameters is not limited, but the length of the
130 complete command line (parameters including spaces etc.) is limited to
131 a fixed number of characters. This limit depends on the architecture
132 and is between 256 and 4096 characters. It is defined in the file
133 ./include/asm/setup.h as COMMAND_LINE_SIZE.
136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
138 Format: { force | off | ht | strict | noirq | rsdt }
139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
143 strict -- Be less tolerant of platforms that are not
144 strictly ACPI specification compliant.
145 rsdt -- prefer RSDT over (default) XSDT
147 See also Documentation/power/pm.txt, pci=noacpi
149 acpi_apic_instance= [ACPI, IOAPIC]
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
155 acpi_sleep= [HW,ACPI] Sleep options
156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
158 See Documentation/power/video.txt for information on
160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
164 old_ordering causes the ACPI 1.0 ordering of the _PTS
165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
172 Format: { level | edge | high | low }
174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
184 Format: <irq>,<irq>...
186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
187 Format: <irq>,<irq>...
189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
199 acpi_serialize [HW,ACPI] force serialization of AML methods
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
204 acpi_use_timer_override [HW,ACPI]
205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
257 acpi_pm_good [X86-32,X86-64]
258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
263 { off | try_unsupported }
264 off: disable AGP support
265 try_unsupported: try to drive unsupported chipsets
266 (may crash computer or cause data corruption)
268 enable_timer_pin_1 [i386,x86-64]
269 Enable PIN 1 of APIC timer
270 Can be useful to work around chipset bugs
271 (in particular on some ATI chipsets).
272 The kernel tries to set a reasonable default.
274 disable_timer_pin_1 [i386,x86-64]
275 Disable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs.
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
282 See header of drivers/scsi/advansys.c.
284 advwdt= [HW,WDT] Advantech WDT
285 Format: <iostart>,<iostop>
287 aedsp16= [HW,OSS] Audio Excel DSP 16
288 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
289 See also header of sound/oss/aedsp16.c.
292 See Documentation/scsi/aha152x.txt.
295 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
298 See Documentation/scsi/aic7xxx.txt.
301 See Documentation/scsi/aic79xx.txt.
303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
306 isolate - enable device isolation (each device, as far
307 as possible, will get its own protection
309 share - put every device behind one IOMMU into the
310 same protection domain
311 fullflush - enable flushing of IO/TLB entries when
312 they are unmapped. Otherwise they are
313 flushed before they will be reused, which
316 amd_iommu_size= [HW,X86-64]
317 Define the size of the aperture for the AMD IOMMU
318 driver. Possible values are:
319 '32M', '64M' (default), '128M', '256M', '512M', '1G'
321 amijoy.map= [HW,JOY] Amiga joystick support
322 Map of devices attached to JOY0DAT and JOY1DAT
324 See also Documentation/kernel/input/joystick.txt
326 analog.map= [HW,JOY] Analog joystick and gamepad support
327 Specifies type or capabilities of an analog joystick
328 connected to one of 16 gameports
329 Format: <type1>,<type2>,..<type16>
332 Power management functions (SPARCstation-4/5 + deriv.)
334 Disable APC CPU standby support. SPARCstation-Fox does
335 not play well with APC CPU idle - disable it if you have
336 APC and your system crashes randomly.
338 apic= [APIC,i386] Advanced Programmable Interrupt Controller
339 Change the output verbosity whilst booting
340 Format: { quiet (default) | verbose | debug }
341 Change the amount of debugging information output
342 when initialising the APIC and IO-APIC components.
344 apm= [APM] Advanced Power Management
345 See header of arch/x86/kernel/apm_32.c.
347 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
348 Format: <io>,<irq>,<nodeID>
352 atarimouse= [HW,MOUSE] Atari Mouse
354 atascsi= [HW,SCSI] Atari SCSI
356 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
357 EzKey and similar keyboards
359 atkbd.reset= [HW] Reset keyboard during initialization
361 atkbd.set= [HW] Select keyboard code set
362 Format: <int> (2 = AT (default), 3 = PS/2)
364 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
367 atkbd.softraw= [HW] Choose between synthetic and real raw mode
368 Format: <bool> (0 = real, 1 = synthetic (default))
370 atkbd.softrepeat= [HW]
371 Use software keyboard repeat
375 baycom_epp= [HW,AX25]
378 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
380 See header of drivers/net/hamradio/baycom_par.c.
382 baycom_ser_fdx= [HW,AX25]
383 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
384 Format: <io>,<irq>,<mode>[,<baud>]
385 See header of drivers/net/hamradio/baycom_ser_fdx.c.
387 baycom_ser_hdx= [HW,AX25]
388 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
389 Format: <io>,<irq>,<mode>
390 See header of drivers/net/hamradio/baycom_ser_hdx.c.
392 boot_delay= Milliseconds to delay each printk during boot.
393 Values larger than 10 seconds (10000) are changed to
397 bootmem_debug [KNL] Enable bootmem allocator debug messages.
399 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
400 bttv.radio= Most important insmod options are available as
402 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
403 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
406 See drivers/scsi/BusLogic.c, comment before function
407 BusLogic_ParseDriverOptions().
409 c101= [NET] Moxa C101 synchronous serial card
411 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
412 Sometimes CPU hardware bugs make them report the cache
413 size incorrectly. The kernel will attempt work arounds
414 to fix known problems, but for some CPUs it is not
415 possible to determine what the correct size should be.
416 This option provides an override for these situations.
418 security= [SECURITY] Choose a security module to enable at boot.
419 If this boot parameter is not specified, only the first
420 security module asking for security registration will be
421 loaded. An invalid security module name will be treated
422 as if no module has been chosen.
425 [SECURITY] Disable capabilities. This would normally
426 be used only if an alternative security model is to be
427 configured. Potentially dangerous and should only be
428 used if you are entirely sure of the consequences.
430 ccw_timeout_log [S390]
431 See Documentation/s390/CommonIO for details.
433 cgroup_disable= [KNL] Disable a particular controller
434 Format: {name of the controller(s) to disable}
435 {Currently supported controllers - "memory"}
437 checkreqprot [SELINUX] Set initial checkreqprot flag value.
438 Format: { "0" | "1" }
439 See security/selinux/Kconfig help text.
440 0 -- check protection applied by kernel (includes
441 any implied execute protection).
442 1 -- check protection requested by application.
443 Default value is set via a kernel config option.
444 Value can be changed at runtime via
445 /selinux/checkreqprot.
448 See Documentation/s390/CommonIO for details.
450 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
452 Forces specified clocksource (if available) to be used
453 when calculating gettimeofday(). If specified
454 clocksource is not available, it defaults to PIT.
455 Format: { pit | tsc | cyclone | pmtmr }
457 clocksource= [GENERIC_TIME] Override the default clocksource
459 Override the default clocksource and use the clocksource
460 with the name specified.
461 Some clocksource names to choose from, depending on
463 [all] jiffies (this is the base, fallback clocksource)
465 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
466 pxa_timer,timer3,32k_counter,timer0_1
468 [X86-32] pit,hpet,tsc,vmi-timer;
469 scx200_hrt on Geode; cyclone on IBM x440
477 clearcpuid=BITNUM [X86]
478 Disable CPUID feature X for the kernel. See
479 arch/x86/include/asm/cpufeature.h for the valid bit
480 numbers. Note the Linux specific bits are not necessarily
481 stable over kernel options, but the vendor specific
483 Also note that user programs calling CPUID directly
484 or using the feature without checking anything
485 will still see it. This just prevents it from
486 being used by the kernel or shown in /proc/cpuinfo.
487 Also note the kernel might malfunction if you disable
490 code_bytes [IA32/X86_64] How many bytes of object code to print
495 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
496 this option disables the debugging code at boot.
498 dma_debug_entries=<number>
499 This option allows to tune the number of preallocated
500 entries for DMA-API debugging code. One entry is
501 required per DMA-API allocation. Use this if the
502 DMA-API debugging code disables itself because the
503 architectural default is too low.
505 hpet= [X86-32,HPET] option to control HPET usage
506 Format: { enable (default) | disable | force |
508 disable: disable HPET and use PIT instead
509 force: allow force enabled of undocumented chips (ICH4,
511 verbose: show contents of HPET registers during setup
513 com20020= [HW,NET] ARCnet - COM20020 chipset
515 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
517 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
521 ARCnet - COM90xx chipset (memory-mapped buffers)
522 Format: <io>[,<irq>[,<memstart>]]
524 condev= [HW,S390] console device
527 console= [KNL] Output console device and options.
529 tty<n> Use the virtual console device <n>.
533 Use the specified serial port. The options are of
534 the form "bbbbpnf", where "bbbb" is the baud rate,
535 "p" is parity ("n", "o", or "e"), "n" is number of
536 bits, and "f" is flow control ("r" for RTS or
537 omit it). Default is "9600n8".
539 See Documentation/serial-console.txt for more
541 Documentation/networking/netconsole.txt for an
544 uart[8250],io,<addr>[,options]
545 uart[8250],mmio,<addr>[,options]
546 Start an early, polled-mode console on the 8250/16550
547 UART at the specified I/O port or MMIO address,
548 switching to the matching ttyS device later. The
549 options are the same as for ttyS, above.
551 If the device connected to the port is not a TTY but a braille
552 device, prepend "brl," before the device type, for instance
554 For now, only VisioBraille is supported.
556 earlycon= [KNL] Output early console device and options.
557 uart[8250],io,<addr>[,options]
558 uart[8250],mmio,<addr>[,options]
559 Start an early, polled-mode console on the 8250/16550
560 UART at the specified I/O port or MMIO address.
561 The options are the same as for ttyS, above.
564 [HW] Never suspend the console
565 Disable suspending of consoles during suspend and
566 hibernate operations. Once disabled, debugging
567 messages can reach various consoles while the rest
568 of the system is being put to sleep (ie, while
569 debugging driver suspend/resume hooks). This may
570 not work reliably with all consoles, but is known
571 to work with serial and VGA consoles.
574 [KNL] Change the default value for
575 /proc/<pid>/coredump_filter.
576 See also Documentation/filesystems/proc.txt.
578 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
580 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
582 crashkernel=nn[KMG]@ss[KMG]
583 [KNL] Reserve a chunk of physical memory to
584 hold a kernel to switch to with kexec on panic.
586 crashkernel=range1:size1[,range2:size2,...][@offset]
587 [KNL] Same as above, but depends on the memory
588 in the running system. The syntax of range is
589 start-[end] where start and end are both
590 a memory unit (amount[KMG]). See also
591 Documentation/kdump/kdump.txt for a example.
596 cs89x0_media= [HW,NET]
597 Format: { rj45 | aui | bnc }
600 See header of drivers/s390/block/dasd_devmap.c.
602 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
603 (one device per port)
604 Format: <port#>,<type>
605 See also Documentation/input/joystick-parport.txt
607 debug [KNL] Enable kernel debugging (events log level).
610 [KNL] verbose self-tests
612 Print debugging info while doing the locking API
614 We default to 0 (no extra messages), setting it to
615 1 will print _a lot_ more information - normally
616 only useful to kernel developers.
618 debug_objects [KNL] Enable object debugging
620 debugpat [X86] Enable PAT debugging
622 decnet.addr= [HW,NET]
623 Format: <area>[,<node>]
624 See also Documentation/networking/decnet.txt.
627 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
628 Change the default blue palette of the console.
629 This is a 16-member array composed of values
633 Format: <green0>,<green1>,<green2>,...,<green15>
634 Change the default green palette of the console.
635 This is a 16-member array composed of values
639 Format: <red0>,<red1>,<red2>,...,<red15>
640 Change the default red palette of the console.
641 This is a 16-member array composed of values
647 Set system-wide default UTF-8 mode for all tty's.
648 Default is 1, i.e. UTF-8 mode is enabled for all
649 newly opened terminals.
652 Set number of hash buckets for dentry cache.
655 IO parameters + enable/disable command.
657 digiepca= [HW,SERIAL]
658 See drivers/char/README.epca and
659 Documentation/serial/digiepca.txt.
661 disable_mtrr_cleanup [X86]
662 enable_mtrr_cleanup [X86]
663 The kernel tries to adjust MTRR layout from continuous
664 to discrete, to make X server driver able to add WB
665 entry later. This parameter enables/disables that.
667 mtrr_chunk_size=nn[KMG] [X86]
668 used for mtrr cleanup. It is largest continous chunk
669 that could hold holes aka. UC entries.
671 mtrr_gran_size=nn[KMG] [X86]
672 Used for mtrr cleanup. It is granularity of mtrr block.
674 Large value could prevent small alignment from
677 mtrr_spare_reg_nr=n [X86]
679 Range: 0,7 : spare reg number
681 Used for mtrr cleanup. It is spare mtrr entries number.
682 Set to 2 or more if your graphical card needs more.
684 disable_mtrr_trim [X86, Intel and AMD only]
685 By default the kernel will trim any uncacheable
686 memory out of your available memory pool based on
687 MTRR settings. This parameter disables that behavior,
688 possibly causing your machine to run very slowly.
690 dmasound= [HW,OSS] Sound subsystem buffers
696 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
698 earlyprintk=serial[,ttySn[,baudrate]]
701 Append ",keep" to not disable it when the real console
704 Only vga or serial or usb debug port at a time.
706 Currently only ttyS0 and ttyS1 are supported.
708 Interaction with the standard serial driver is not
711 The VGA output is eventually overwritten by the real
717 Format: {"off" | "on" | "skip[mbr]"}
719 eisa_irq_edge= [PARISC,HW]
720 See header of drivers/parisc/eisa.c.
723 See comment before function elanfreq_setup() in
724 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
727 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
728 See Documentation/block/as-iosched.txt and
729 Documentation/block/deadline-iosched.txt for details.
731 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
732 Specifies physical address of start of kernel core
733 image elf header. Generally kexec loader will
734 pass this option to capture kernel.
735 See Documentation/kdump/kdump.txt for details.
737 enforcing [SELINUX] Set initial enforcing status.
739 See security/selinux/Kconfig help text.
740 0 -- permissive (log only, no denials).
741 1 -- enforcing (deny and log).
743 Value can be changed at runtime via /selinux/enforce.
745 ether= [HW,NET] Ethernet cards parameters
746 This option is obsoleted by the "netdev=" option, which
747 has equivalent usage. See its documentation for details.
749 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
754 fail_make_request=[KNL]
755 General fault injection mechanism.
756 Format: <interval>,<probability>,<space>,<times>
757 See also /Documentation/fault-injection/.
760 See header of drivers/scsi/fd_mcs.c.
763 See header of drivers/scsi/fdomain.c.
766 See Documentation/blockdev/floppy.txt.
768 force_pal_cache_flush
769 [IA-64] Avoid check_sal_cache_flush which may hang on
770 buggy SAL_CACHE_FLUSH implementations. Using this
771 parameter will force ia64_sal_cache_flush to call
772 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
775 [ftrace] will set and start the specified tracer
776 as early as possible in order to facilitate early
780 [ftrace] will dump the trace buffers on oops.
783 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
784 support via parallel port (up to 5 devices per port)
785 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
786 See also Documentation/input/joystick-parport.txt
790 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
795 See header of drivers/scsi/gdth.c.
797 gpt [EFI] Forces disk with valid GPT signature but
798 invalid Protective MBR to be treated as GPT.
802 hashdist= [KNL,NUMA] Large hashes allocated during boot
803 are distributed across NUMA nodes. Defaults on
804 for IA-64, off otherwise.
805 Format: 0 | 1 (for off | on)
807 hcl= [IA-64] SGI's Hardware Graph compatibility layer
809 hd= [EIDE] (E)IDE hard drive subsystem geometry
810 Format: <cyl>,<head>,<sect>
812 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
813 size of <nn>. This works even on boxes that have no
814 highmem otherwise. This also works to reduce highmem
815 size on bigger boxes.
817 highres= [KNL] Enable/disable high resolution timer mode.
818 Valid parameters: "on", "off"
822 See Documentation/isdn/README.HiSax.
824 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
825 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
826 On x86-64 and powerpc, this option can be specified
827 multiple times interleaved with hugepages= to reserve
828 huge pages of different sizes. Valid pages sizes on
829 x86-64 are 2M (when the CPU supports "pse") and 1G
830 (when the CPU supports the "pdpe1gb" cpuinfo flag)
831 Note that 1GB pages can only be allocated at boot time
832 using hugepages= and not freed afterwards.
834 [same as hugepagesz=] The size of the default
835 HugeTLB page size. This is the size represented by
836 the legacy /proc/ hugepages APIs, used for SHM, and
837 default size when mounting hugetlbfs filesystems.
838 Defaults to the default architecture's huge page size
843 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
844 terminal devices. Valid values: 0..8
845 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
846 If specified, z/VM IUCV HVC accepts connections
847 from listed z/VM user IDs only.
849 i8042.debug [HW] Toggle i8042 debug mode
850 i8042.direct [HW] Put keyboard port into non-translated mode
851 i8042.dumbkbd [HW] Pretend that controller can only read data from
852 keyboard and cannot control its state
853 (Don't attempt to blink the leds)
854 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
855 i8042.nokbd [HW] Don't check/create keyboard port
856 i8042.noloop [HW] Disable the AUX Loopback command while probing
858 i8042.nomux [HW] Don't check presence of an active multiplexing
860 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
863 [HW] Frequency with which keyboard LEDs should blink
864 when kernel panics (default is 0.5 sec)
865 i8042.reset [HW] Reset the controller during init and cleanup
866 i8042.unlock [HW] Unlock (ignore) the keylock
870 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
871 indicates that the driver is running on unsupported
873 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
874 does not match list of supported models.
876 [HW] Report power status in /proc/i8k
877 (disabled by default)
878 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
881 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
882 See Documentation/mca.txt.
885 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
887 ide-core.nodma= [HW] (E)IDE subsystem
888 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
889 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
890 .chs .ignore_cable are additional options
891 See Documentation/ide/ide.txt.
893 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
894 See Documentation/ide/ide.txt.
897 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
898 Poll forces a polling idle loop that can slightly
899 improve the performance of waking up a idle CPU, but
900 will use a lot of power and make the system run hot.
902 idle=mwait: On systems which support MONITOR/MWAIT but
903 the kernel chose to not use it because it doesn't save
904 as much power as a normal idle loop, use the
905 MONITOR/MWAIT idle loop anyways. Performance should be
906 the same as idle=poll.
907 idle=halt: Halt is forced to be used for CPU idle.
908 In such case C2/C3 won't be used again.
909 idle=nomwait: Disable mwait for CPU C-states
911 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
912 Claim all unknown PCI IDE storage controllers.
914 ignore_loglevel [KNL]
915 Ignore loglevel setting - this will print /all/
916 kernel messages to the console. Useful for debugging.
919 Set number of hash buckets for inode cache.
922 Format: { "0" | "1" }
923 0 -- integrity auditing messages. (Default)
924 1 -- enable informational integrity auditing messages.
927 Formt: { "sha1" | "md5" }
931 See header of drivers/scsi/in2000.c.
935 Run specified binary instead of /sbin/init as init
938 initcall_debug [KNL] Trace initcalls as they are executed. Useful
939 for working out where the kernel is dying during
942 initrd= [BOOT] Specify the location of the initial ramdisk
944 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
949 iomem= Disable strict checking of access to MMIO memory
950 strict regions from userspace.
966 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
968 Enable intel iommu driver.
970 Disable intel iommu driver.
971 igfx_off [Default Off]
972 By default, gfx is mapped as normal device. If a gfx
973 device has a dedicated DMAR unit, the DMAR unit is
974 bypassed by not enabling DMAR with this option. In
975 this case, gfx device will use physical address for
978 With this option iommu will not optimize to look
979 for io virtual address below 32 bit forcing dual
980 address cycle on pci bus for cards supporting greater
981 than 32 bit addressing. The default is to look
982 for translation below 32 bit and if not available
983 then look in the higher range.
985 With this option on every unmap_single operation will
986 result in a hardware IOTLB flush operation as opposed
987 to batching them for performance.
989 io_delay= [X86-32,X86-64] I/O delay method
991 Standard port 0x80 based delay
993 Alternate port 0xed based delay (needed on some systems)
995 Simple two microseconds delay
999 io7= [HW] IO7 for Marvel based alpha systems
1000 See comment before marvel_specify_io7 in
1001 arch/alpha/kernel/core_marvel.c.
1004 See Documentation/filesystems/nfsroot.txt.
1006 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1007 See comment before ip2_setup() in
1008 drivers/char/ip2/ip2base.c.
1010 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1011 See header of drivers/scsi/ips.c.
1013 ports= [IP_VS_FTP] IPVS ftp helper module
1015 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1017 Format: <port>,<port>....
1020 When an interrupt is not handled search all handlers
1021 for it. Intended to get systems with badly broken
1025 When an interrupt is not handled search all handlers
1026 for it. Also check all handlers each timer
1027 interrupt. Intended to get systems with badly broken
1031 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1033 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1035 <cpu number>,...,<cpu number>
1037 <cpu number>-<cpu number>
1038 (must be a positive range in ascending order)
1040 <cpu number>,...,<cpu number>-<cpu number>
1042 This option can be used to specify one or more CPUs
1043 to isolate from the general SMP balancing and scheduling
1044 algorithms. You can move a process onto or off an
1045 "isolated" CPU via the CPU affinity syscalls or cpuset.
1046 <cpu number> begins at 0 and the maximum value is
1047 "number of CPUs in system - 1".
1049 This option is the preferred way to isolate CPUs. The
1050 alternative -- manually setting the CPU mask of all
1051 tasks in the system -- can cause problems and
1052 suboptimal load balancer performance.
1056 js= [HW,JOY] Analog joystick
1057 See Documentation/input/joystick.txt.
1059 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1060 specifies the amount of memory usable by the kernel
1061 for non-movable allocations. The requested amount is
1062 spread evenly throughout all nodes in the system. The
1063 remaining memory in each node is used for Movable
1064 pages. In the event, a node is too small to have both
1065 kernelcore and Movable pages, kernelcore pages will
1066 take priority and other nodes will have a larger number
1067 of kernelcore pages. The Movable zone is used for the
1068 allocation of pages that may be reclaimed or moved
1069 by the page migration subsystem. This means that
1070 HugeTLB pages may not be allocated from this zone.
1071 Note that allocations like PTEs-from-HighMem still
1072 use the HighMem zone if it exists, and the Normal
1073 zone if it does not.
1075 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1076 is similar to kernelcore except it specifies the
1077 amount of memory used for migratable allocations.
1078 If both kernelcore and movablecore is specified,
1079 then kernelcore will be at *least* the specified
1080 value but may be more. If movablecore on its own
1081 is specified, the administrator must be careful
1082 that the amount of memory usable for all allocations
1087 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1090 kgdboc= [HW] kgdb over consoles.
1091 Requires a tty driver that supports console polling.
1092 (only serial suported for now)
1093 Format: <serial_device>[,baud]
1095 kmac= [MIPS] korina ethernet MAC address.
1096 Configure the RouterBoard 532 series on-chip
1097 Ethernet adapter MAC address.
1103 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1106 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1109 libata.dma= [LIBATA] DMA control
1110 libata.dma=0 Disable all PATA and SATA DMA
1111 libata.dma=1 PATA and SATA Disk DMA only
1112 libata.dma=2 ATAPI (CDROM) DMA only
1113 libata.dma=4 Compact Flash DMA only
1114 Combinations also work, so libata.dma=3 enables DMA
1115 for disks and CDROMs, but not CFs.
1117 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1121 libata.force= [LIBATA] Force configurations. The format is comma
1122 separated list of "[ID:]VAL" where ID is
1123 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1124 matching port, link or device. Basically, it matches
1125 the ATA ID string printed on console by libata. If
1126 the whole ID part is omitted, the last PORT and DEVICE
1127 values are used. If ID hasn't been specified yet, the
1128 configuration applies to all ports, links and devices.
1130 If only DEVICE is omitted, the parameter applies to
1131 the port and all links and devices behind it. DEVICE
1132 number of 0 either selects the first device or the
1133 first fan-out link behind PMP device. It does not
1134 select the host link. DEVICE number of 15 selects the
1135 host link and device attached to it.
1137 The VAL specifies the configuration to force. As long
1138 as there's no ambiguity shortcut notation is allowed.
1139 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1140 The following configurations can be forced.
1142 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1143 Any ID with matching PORT is used.
1145 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1147 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1148 udma[/][16,25,33,44,66,100,133] notation is also
1151 * [no]ncq: Turn on or off NCQ.
1153 * nohrst, nosrst, norst: suppress hard, soft
1156 If there are multiple matching configurations changing
1157 the same attribute, the last one is used.
1159 lmb=debug [KNL] Enable lmb debug messages.
1161 load_ramdisk= [RAM] List of ramdisks to load from floppy
1162 See Documentation/blockdev/ramdisk.txt.
1164 lockd.nlm_grace_period=P [NFS] Assign grace period.
1167 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1170 lockd.nlm_timeout=T [NFS] Assign timeout value.
1173 lockd.nlm_udpport=M [NFS] Assign UDP port.
1176 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1179 loglevel= All Kernel Messages with a loglevel smaller than the
1180 console loglevel will be printed to the console. It can
1181 also be changed with klogd or other programs. The
1182 loglevels are defined as follows:
1184 0 (KERN_EMERG) system is unusable
1185 1 (KERN_ALERT) action must be taken immediately
1186 2 (KERN_CRIT) critical conditions
1187 3 (KERN_ERR) error conditions
1188 4 (KERN_WARNING) warning conditions
1189 5 (KERN_NOTICE) normal but significant condition
1190 6 (KERN_INFO) informational
1191 7 (KERN_DEBUG) debug-level messages
1193 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1194 Format: { n | nk | nM }
1195 n must be a power of two. The default size
1196 is set in the kernel config file.
1198 logo.nologo [FB] Disables display of the built-in Linux logo.
1199 This may be used to provide more screen space for
1200 kernel log messages and is useful when debugging
1201 kernel boot problems.
1203 lp=0 [LP] Specify parallel ports to use, e.g,
1204 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1205 lp=reset first parallel port). 'lp=0' disables the
1206 lp=auto printer driver. 'lp=reset' (which can be
1207 specified in addition to the ports) causes
1208 attached printers to be reset. Using
1209 lp=port1,port2,... specifies the parallel ports
1210 to associate lp devices with, starting with
1211 lp0. A port specification may be 'none' to skip
1212 that lp device, or a parport name such as
1213 'parport0'. Specifying 'lp=auto' instead of a
1214 port specification list means that device IDs
1215 from each port should be examined, to see if
1216 an IEEE 1284-compliant printer is attached; if
1217 so, the driver will manage that printer.
1218 See also header of drivers/char/lp.c.
1221 Sets loops_per_jiffy to given constant, thus avoiding
1222 time-consuming boot-time autodetection (up to 250 ms per
1223 CPU). 0 enables autodetection (default). To determine
1224 the correct value for your kernel, boot with normal
1225 autodetection and see what value is printed. Note that
1226 on SMP systems the preset will be applied to all CPUs,
1227 which is likely to cause problems if your CPUs need
1228 significantly divergent settings. An incorrect value
1229 will cause delays in the kernel to be wrong, leading to
1230 unpredictable I/O errors and other breakage. Although
1231 unlikely, in the extreme case this might damage your
1235 Format: <io>,<irq>,<dma>
1237 mac5380= [HW,SCSI] Format:
1238 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1240 machvec= [IA64] Force the use of a particular machine-vector
1241 (machvec) in a generic kernel.
1242 Example: machvec=hpzx1_swiotlb
1244 max_loop= [LOOP] Maximum number of loopback devices that can
1248 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1249 should make use of. maxcpus=n : n >= 0 limits the
1250 kernel to using 'n' processors. n=0 is a special case,
1251 it is equivalent to "nosmp", which also disables
1254 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1255 or equal to this physical address is ignored.
1257 max_luns= [SCSI] Maximum number of LUNs to probe.
1258 Should be between 1 and 2^32-1.
1261 [SCSI] Maximum number of LUNs received.
1262 Should be between 1 and 16384.
1266 mce [X86-32] Machine Check Exception
1268 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1270 md= [HW] RAID subsystems devices and level
1271 See Documentation/md.txt.
1274 Format: <first>,<last>
1275 Specifies range of consoles to be captured by the MDA.
1277 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1278 Amount of memory to be used when the kernel is not able
1279 to see the whole system memory or for test.
1280 [X86-32] Use together with memmap= to avoid physical
1281 address space collisions. Without memmap= PCI devices
1282 could be placed at addresses belonging to unused RAM.
1284 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1288 [KNL,SH] Allow user to override the default size for
1289 per-device physically contiguous DMA buffers.
1291 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1292 E820 memory map, as specified by the user.
1293 Such memmap=exactmap lines can be constructed based on
1294 BIOS output or other requirements. See the memmap=nn@ss
1297 memmap=nn[KMG]@ss[KMG]
1298 [KNL] Force usage of a specific region of memory
1299 Region of memory to be used, from ss to ss+nn.
1301 memmap=nn[KMG]#ss[KMG]
1302 [KNL,ACPI] Mark specific memory as ACPI data.
1303 Region of memory to be used, from ss to ss+nn.
1305 memmap=nn[KMG]$ss[KMG]
1306 [KNL,ACPI] Mark specific memory as reserved.
1307 Region of memory to be used, from ss to ss+nn.
1308 Example: Exclude memory from 0x18690000-0x1869ffff
1309 memmap=64K$0x18690000
1311 memmap=0x10000$0x18690000
1313 memory_corruption_check=0/1 [X86]
1314 Some BIOSes seem to corrupt the first 64k of
1315 memory when doing things like suspend/resume.
1316 Setting this option will scan the memory
1317 looking for corruption. Enabling this will
1318 both detect corruption and prevent the kernel
1319 from using the memory being corrupted.
1320 However, its intended as a diagnostic tool; if
1321 repeatable BIOS-originated corruption always
1322 affects the same memory, you can use memmap=
1323 to prevent the kernel from using that memory.
1325 memory_corruption_check_size=size [X86]
1326 By default it checks for corruption in the low
1327 64k, making this memory unavailable for normal
1328 use. Use this parameter to scan for
1329 corruption in more or less memory.
1331 memory_corruption_check_period=seconds [X86]
1332 By default it checks for corruption every 60
1333 seconds. Use this parameter to check at some
1334 other rate. 0 disables periodic checking.
1336 memtest= [KNL,X86] Enable memtest
1338 default : 0 <disable>
1339 Specifies the number of memtest passes to be
1340 performed. Each pass selects another test
1341 pattern from a given set of patterns. Memtest
1342 fills the memory with this pattern, validates
1343 memory contents and reserves bad memory
1344 regions that are detected.
1346 meye.*= [HW] Set MotionEye Camera parameters
1347 See Documentation/video4linux/meye.txt.
1349 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1350 Multi-Function General Purpose Timers on AMD Geode
1353 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1354 the BIOS has incorrectly applied a workaround. TinyBIOS
1355 version 0.98 is known to be affected, 0.99 fixes the
1356 problem by letting the user disable the workaround.
1360 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1361 physical address is ignored.
1364 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1365 parameter allows control of the logging verbosity for
1366 the additional memory initialisation checks. A value
1367 of 0 disables mminit logging and a level of 4 will
1368 log everything. Information is printed at KERN_DEBUG
1369 so loglevel=8 may also need to be specified.
1372 [MOUSE] Maximum time between finger touching and
1373 leaving touchpad surface for touch to be considered
1374 a tap and be reported as a left button click (for
1375 touchpads working in absolute mode only).
1377 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1378 reporting absolute coordinates, such as tablets
1379 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1380 reporting absolute coordinates, such as tablets
1385 MTD_Partition= [MTD]
1386 Format: <name>,<region-number>,<size>,<offset>
1388 MTD_Region= [MTD] Format:
1389 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1392 See drivers/mtd/cmdlinepart.c.
1395 ARM/S3C2412 JIVE boot control
1397 See arch/arm/mach-s3c2412/mach-jive.c
1399 mtouchusb.raw_coordinates=
1400 [HW] Make the MicroTouch USB driver use raw coordinates
1401 ('y', default) or cooked coordinates ('n')
1403 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1406 See header of drivers/scsi/NCR_D700.c.
1410 ncr53c400= [HW,SCSI]
1412 ncr53c400a= [HW,SCSI]
1414 ncr53c406a= [HW,SCSI]
1416 ncr53c8xx= [HW,SCSI]
1418 netdev= [NET] Network devices parameters
1419 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1420 Note that mem_start is often overloaded to mean
1421 something different and driver-specific.
1422 This usage is only documented in each driver source
1426 [NETFILTER] Enable connection tracking flow accounting
1427 0 to disable accounting
1428 1 to enable accounting
1429 Default value depends on CONFIG_NF_CT_ACCT that is
1430 going to be removed in 2.6.29.
1433 See Documentation/filesystems/nfsroot.txt.
1435 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1436 See Documentation/filesystems/nfsroot.txt.
1438 nfs.callback_tcpport=
1439 [NFS] set the TCP port on which the NFSv4 callback
1440 channel should listen.
1442 nfs.idmap_cache_timeout=
1443 [NFS] set the maximum lifetime for idmapper cache
1447 [NFS] enable 64-bit inode numbers.
1448 If zero, the NFS client will fake up a 32-bit inode
1449 number for the readdir() and stat() syscalls instead
1450 of returning the full 64-bit number.
1451 The default is to return 64-bit inode numbers.
1453 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1454 when a NMI is triggered.
1455 Format: [state][,regs][,debounce][,die]
1457 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1458 Format: [panic,][num]
1460 0 - turn nmi_watchdog off
1461 1 - use the IO-APIC timer for the NMI watchdog
1462 2 - use the local APIC for the NMI watchdog using
1463 a performance counter. Note: This will use one performance
1464 counter and the local APIC's performance vector.
1465 When panic is specified panic when an NMI watchdog timeout occurs.
1466 This is useful when you use a panic=... timeout and need the box
1468 Instead of 1 and 2 it is possible to use the following
1469 symbolic names: lapic and ioapic
1470 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1472 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1473 emulation library even if a 387 maths coprocessor
1476 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1477 caches in the slab allocator. Saves per-node memory,
1478 but will impact performance.
1482 noapic [SMP,APIC] Tells the kernel to not make use of any
1483 IOAPICs that may be present in the system.
1485 nobats [PPC] Do not use BATs for mapping kernel lowmem
1486 on "Classic" PPC cores.
1490 nodelayacct [KNL] Disable per-task delay accounting
1492 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1494 nodsp [SH] Disable hardware DSP at boot time.
1496 noefi [X86-32,X86-64] Disable EFI runtime services support.
1500 noexec [X86-32,X86-64]
1501 On X86-32 available only on PAE configured kernels.
1502 noexec=on: enable non-executable mappings (default)
1503 noexec=off: disable non-executable mappings
1506 This affects only 32-bit executables.
1507 noexec32=on: enable non-executable mappings (default)
1508 read doesn't imply executable mappings
1509 noexec32=off: disable non-executable mappings
1510 read implies executable mappings
1512 nofpu [SH] Disable hardware FPU at boot time.
1514 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1515 register save and restore. The kernel will only save
1516 legacy floating-point registers on task switch.
1518 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1522 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1523 instruction doesn't work correctly and not to
1526 no_file_caps Tells the kernel not to honor file capabilities. The
1527 only way then for a file to be executed with privilege
1528 is to be setuid root or executed by root.
1530 nohalt [IA-64] Tells the kernel not to use the power saving
1531 function PAL_HALT_LIGHT when idle. This increases
1532 power-consumption. On the positive side, it reduces
1533 interrupt wake-up latency, which may improve performance
1534 in certain environments such as networked servers or
1537 nohz= [KNL] Boottime enable/disable dynamic ticks
1538 Valid arguments: on, off
1541 noirqdebug [X86-32] Disables the code which attempts to detect and
1542 disable unhandled interrupt sources.
1544 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1545 broken timer IRQ sources.
1547 noisapnp [ISAPNP] Disables ISA PnP code.
1549 noinitrd [RAM] Tells the kernel not to load any configured
1554 nojitter [IA64] Disables jitter checking for ITC timers.
1556 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1558 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1560 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1562 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1563 default x2apic cluster mode on platforms
1566 noltlbs [PPC] Do not use large page/tlb entries for kernel
1567 lowmem mapping on PPC40x.
1569 nomca [IA-64] Disable machine check abort handling
1571 nomce [X86-32] Machine Check Exception
1573 nomfgpt [X86-32] Disable Multi-Function General Purpose
1574 Timer usage (for AMD Geode machines).
1576 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1578 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1579 with UP alternatives
1581 noresidual [PPC] Don't use residual data on PReP machines.
1583 noresume [SWSUSP] Disables resume and restores original swap
1586 no-scroll [VGA] Disables scrollback.
1587 This is required for the Braillex ib80-piezo Braille
1588 reader made by F.H. Papenmeier (Germany).
1592 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1594 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1595 and disable the IO APIC. legacy for "maxcpus=0".
1597 nosoftlockup [KNL] Disable the soft-lockup detector.
1599 noswapaccount [KNL] Disable accounting of swap in memory resource
1600 controller. (See Documentation/controllers/memory.txt)
1602 nosync [HW,M68K] Disables sync negotiation for all devices.
1604 notsc [BUGS=X86-32] Disable Time Stamp Counter
1606 nousb [USB] Disable the USB subsystem
1610 nptcg= [IA64] Override max number of concurrent global TLB
1611 purges which is reported from either PAL_VM_SUMMARY or
1614 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1615 one of ['zone', 'node', 'default'] can be specified
1616 This can be set from sysctl after boot.
1617 See Documentation/sysctl/vm.txt for details.
1619 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1621 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1622 See Documentation/debugging-via-ohci1394.txt for more
1625 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1626 Rather than timing out after 20 ms if an EC
1627 command is not properly ACKed, override the length
1628 of the timeout. We have interrupts disabled while
1629 waiting for the ACK, so if this is set too high
1630 interrupts *may* be lost!
1635 oprofile.timer= [HW]
1636 Use timer interrupt instead of performance counters
1638 osst= [HW,SCSI] SCSI Tape Driver
1639 Format: <buffer_size>,<write_threshold>
1640 See also Documentation/scsi/st.txt.
1642 panic= [KNL] Kernel behaviour on panic
1645 parkbd.port= [HW] Parallel port number the keyboard adapter is
1646 connected to, default is 0.
1648 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1649 0 for XT, 1 for AT (default is AT).
1652 parport= [HW,PPT] Specify parallel ports. 0 disables.
1653 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1654 Use 'auto' to force the driver to use any
1655 IRQ/DMA settings detected (the default is to
1656 ignore detected IRQ/DMA settings because of
1657 possible conflicts). You can specify the base
1658 address, IRQ, and DMA settings; IRQ and DMA
1659 should be numbers, or 'auto' (for using detected
1660 settings on that particular port), or 'nofifo'
1661 (to avoid using a FIFO even if it is detected).
1662 Parallel ports are assigned in the order they
1663 are specified on the command line, starting
1666 parport_init_mode= [HW,PPT]
1667 Configure VIA parallel port to operate in
1668 a specific mode. This is necessary on Pegasos
1669 computer where firmware has no options for setting
1670 up parallel port mode and sets it to spp.
1671 Currently this function knows 686a and 8231 chips.
1672 Format: [spp|ps2|epp|ecp|ecpepp]
1674 pas2= [HW,OSS] Format:
1675 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1678 See header of drivers/scsi/pas16.c.
1681 Halt all CPUs after the first oops has been printed for
1682 the specified number of seconds. This is to be used if
1683 your oopses keep scrolling off the screen.
1688 See header of drivers/block/paride/pcd.c.
1689 See also Documentation/blockdev/paride.txt.
1691 pci=option[,option...] [PCI] various PCI subsystem options:
1692 off [X86] don't probe for the PCI bus
1693 bios [X86-32] force use of PCI BIOS, don't access
1694 the hardware directly. Use this if your machine
1695 has a non-standard PCI host bridge.
1696 nobios [X86-32] disallow use of PCI BIOS, only direct
1697 hardware access methods are allowed. Use this
1698 if you experience crashes upon bootup and you
1699 suspect they are caused by the BIOS.
1700 conf1 [X86] Force use of PCI Configuration
1702 conf2 [X86] Force use of PCI Configuration
1704 noaer [PCIE] If the PCIEAER kernel config parameter is
1705 enabled, this kernel boot option can be used to
1706 disable the use of PCIE advanced error reporting.
1707 nodomains [PCI] Disable support for multiple PCI
1708 root domains (aka PCI segments, in ACPI-speak).
1709 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1711 nomsi [MSI] If the PCI_MSI kernel config parameter is
1712 enabled, this kernel boot option can be used to
1713 disable the use of MSI interrupts system-wide.
1714 noioapicquirk [APIC] Disable all boot interrupt quirks.
1715 Safety option to keep boot IRQs enabled. This
1716 should never be necessary.
1717 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1718 primary IO-APIC for bridges that cannot disable
1719 boot IRQs. This fixes a source of spurious IRQs
1720 when the system masks IRQs.
1721 noioapicreroute [APIC] Disable workaround that uses the
1722 boot IRQ equivalent of an IRQ that connects to
1723 a chipset where boot IRQs cannot be disabled.
1724 The opposite of ioapicreroute.
1725 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1726 routing table. These calls are known to be buggy
1727 on several machines and they hang the machine
1728 when used, but on other computers it's the only
1729 way to get the interrupt routing table. Try
1730 this option if the kernel is unable to allocate
1731 IRQs or discover secondary PCI buses on your
1733 rom [X86] Assign address space to expansion ROMs.
1734 Use with caution as certain devices share
1735 address decoders between ROMs and other
1737 norom [X86] Do not assign address space to
1738 expansion ROMs that do not already have
1739 BIOS assigned address ranges.
1740 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1741 assigned automatically to PCI devices. You can
1742 make the kernel exclude IRQs of your ISA cards
1744 pirqaddr=0xAAAAA [X86] Specify the physical address
1745 of the PIRQ table (normally generated
1746 by the BIOS) if it is outside the
1747 F0000h-100000h range.
1748 lastbus=N [X86] Scan all buses thru bus #N. Can be
1749 useful if the kernel is unable to find your
1750 secondary buses and you want to tell it
1751 explicitly which ones they are.
1752 assign-busses [X86] Always assign all PCI bus
1753 numbers ourselves, overriding
1754 whatever the firmware may have done.
1755 usepirqmask [X86] Honor the possible IRQ mask stored
1756 in the BIOS $PIR table. This is needed on
1757 some systems with broken BIOSes, notably
1758 some HP Pavilion N5400 and Omnibook XE3
1759 notebooks. This will have no effect if ACPI
1760 IRQ routing is enabled.
1761 noacpi [X86] Do not use ACPI for IRQ routing
1762 or for PCI scanning.
1763 use_crs [X86] Use _CRS for PCI resource
1765 routeirq Do IRQ routing for all PCI devices.
1766 This is normally done in pci_enable_device(),
1767 so this option is a temporary workaround
1768 for broken drivers that don't call it.
1769 skip_isa_align [X86] do not align io start addr, so can
1770 handle more pci cards
1771 firmware [ARM] Do not re-enumerate the bus but instead
1772 just use the configuration from the
1773 bootloader. This is currently used on
1774 IXP2000 systems where the bus has to be
1775 configured a certain way for adjunct CPUs.
1776 noearly [X86] Don't do any early type 1 scanning.
1777 This might help on some broken boards which
1778 machine check when some devices' config space
1779 is read. But various workarounds are disabled
1780 and some IOMMU drivers will not work.
1781 bfsort Sort PCI devices into breadth-first order.
1782 This sorting is done to get a device
1783 order compatible with older (<= 2.4) kernels.
1784 nobfsort Don't sort PCI devices into breadth-first order.
1785 cbiosize=nn[KMG] The fixed amount of bus space which is
1786 reserved for the CardBus bridge's IO window.
1787 The default value is 256 bytes.
1788 cbmemsize=nn[KMG] The fixed amount of bus space which is
1789 reserved for the CardBus bridge's memory
1790 window. The default value is 64 megabytes.
1792 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1795 force Enable ASPM even on devices that claim not to support it.
1796 WARNING: Forcing ASPM on may cause system lockups.
1798 pcmv= [HW,PCMCIA] BadgePAD 4
1801 See Documentation/blockdev/paride.txt.
1803 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1806 See arch/parisc/kernel/pdc_chassis.c
1809 See Documentation/blockdev/paride.txt.
1812 See Documentation/blockdev/paride.txt.
1814 pirq= [SMP,APIC] Manual mp-table setup
1815 See Documentation/x86/i386/IO-APIC.txt.
1817 plip= [PPT,NET] Parallel port network link
1818 Format: { parport<nr> | timid | 0 }
1819 See also Documentation/parport.txt.
1821 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1822 Override pmtimer IOPort with a hex value.
1826 Enable PNP debug messages. This depends on the
1827 CONFIG_PNP_DEBUG_MESSAGES option.
1833 { on | off | curr | res | no-curr | no-res }
1836 [ISAPNP] Exclude IRQs for the autoconfiguration
1839 [ISAPNP] Exclude DMAs for the autoconfiguration
1841 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1842 Ranges are in pairs (I/O port base and size).
1845 [ISAPNP] Exclude memory regions for the
1847 Ranges are in pairs (memory base and size).
1849 print-fatal-signals=
1850 [KNL] debug: print fatal signals
1851 print-fatal-signals=1: print segfault info to
1855 printk.time= Show timing data prefixed to each printk message line
1856 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1858 profile= [KNL] Enable kernel profiling via /proc/profile
1859 Format: [schedule,]<number>
1860 Param: "schedule" - profile schedule points.
1861 Param: <number> - step/bucket size as a power of 2 for
1862 statistical time based profiling.
1863 Param: "sleep" - profile D-state sleeping (millisecs).
1864 Requires CONFIG_SCHEDSTATS
1865 Param: "kvm" - profile VM exits.
1867 processor.max_cstate= [HW,ACPI]
1868 Limit processor to maximum C-state
1869 max_cstate=9 overrides any DMI blacklist limit.
1871 processor.nocst [HW,ACPI]
1872 Ignore the _CST method to determine C-states,
1873 instead using the legacy FADT method
1875 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1877 See Documentation/blockdev/ramdisk.txt.
1879 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1880 probe for; one of (bare|imps|exps|lifebook|any).
1881 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1883 psmouse.resetafter= [HW,MOUSE]
1884 Try to reset the device after so many bad packets
1887 [HW,MOUSE] Set desired mouse resolution, in dpi.
1888 psmouse.smartscroll=
1889 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1890 0 = disabled, 1 = enabled (default).
1892 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1894 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1897 See Documentation/blockdev/paride.txt.
1900 [KNL] Number of legacy pty's. Overwrites compiled-in
1903 quiet [KNL] Disable most log messages
1908 See Documentation/md.txt.
1910 ramdisk_blocksize= [RAM]
1911 See Documentation/blockdev/ramdisk.txt.
1913 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1914 See Documentation/blockdev/ramdisk.txt.
1916 rcupdate.blimit= [KNL,BOOT]
1917 Set maximum number of finished RCU callbacks to process
1920 rcupdate.qhimark= [KNL,BOOT]
1921 Set threshold of queued
1922 RCU callbacks over which batch limiting is disabled.
1924 rcupdate.qlowmark= [KNL,BOOT]
1925 Set threshold of queued RCU callbacks below which
1926 batch limiting is re-enabled.
1930 Run specified binary instead of /init from the ramdisk,
1931 used for early userspace startup. See initrd.
1933 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1934 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1935 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1938 [KNL, SMP] Set scheduler's default relax_domain_level.
1939 See Documentation/cpusets.txt.
1941 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1943 reservetop= [X86-32]
1945 Reserves a hole at the top of the kernel virtual
1948 reset_devices [KNL] Force drivers to reset the underlying device
1949 during initialization.
1952 Specify the partition device for software suspend
1954 resume_offset= [SWSUSP]
1955 Specify the offset from the beginning of the partition
1956 given by "resume=" at which the swap header is located,
1957 in <PAGE_SIZE> units (needed only for swap files).
1958 See Documentation/power/swsusp-and-swap-files.txt
1960 retain_initrd [RAM] Keep initrd memory after extraction
1962 rhash_entries= [KNL,NET]
1963 Set number of hash buckets for route cache
1965 riscom8= [HW,SERIAL]
1966 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1968 ro [KNL] Mount root device read-only on boot
1970 root= [KNL] Root filesystem
1972 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1973 mount the root filesystem
1975 rootflags= [KNL] Set root filesystem mount option string
1977 rootfstype= [KNL] Set root filesystem type
1979 rootwait [KNL] Wait (indefinitely) for root device to show up.
1980 Useful for devices that are detected asynchronously
1981 (e.g. USB and MMC devices).
1983 root_plug.vendor_id=
1984 [ROOTPLUG] Override the default vendor ID
1986 root_plug.product_id=
1987 [ROOTPLUG] Override the default product ID
1990 [ROOTPLUG] Enable debugging output
1992 rw [KNL] Mount root device read-write on boot
1994 S [KNL] Run init in single mode
1997 See drivers/net/irda/sa1100_ir.c.
1999 sbni= [NET] Granch SBNI12 leased line adapter
2001 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2002 Format: <io>[,<timeout>[,<isapnp>]]
2004 scsi_debug_*= [SCSI]
2005 See drivers/scsi/scsi_debug.c.
2007 scsi_default_dev_flags=
2008 [SCSI] SCSI default device flags
2011 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2012 Format: <vendor>:<model>:<flags>
2013 (flags are integer value)
2015 scsi_logging_level= [SCSI] a bit mask of logging levels
2016 See drivers/scsi/scsi_logging.h for bits. Also
2017 settable via sysctl at dev.scsi.logging_level
2018 (/proc/sys/dev/scsi/logging_level).
2019 There is also a nice 'scsi_logging_level' script in the
2020 S390-tools package, available for download at
2021 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2023 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2024 discovered. async scans them in kernel threads,
2025 allowing boot to proceed. none ignores them, expecting
2026 user space to do the scan.
2028 selinux [SELINUX] Disable or enable SELinux at boot time.
2029 Format: { "0" | "1" }
2030 See security/selinux/Kconfig help text.
2033 Default value is set via kernel config option.
2034 If enabled at boot time, /selinux/disable can be used
2035 later to disable prior to initial policy load.
2037 selinux_compat_net =
2038 [SELINUX] Set initial selinux_compat_net flag value.
2039 Format: { "0" | "1" }
2040 0 -- use new secmark-based packet controls
2041 1 -- use legacy packet controls
2042 Default value is 0 (preferred).
2043 Value can be changed at runtime via
2044 /selinux/compat_net.
2046 serialnumber [BUGS=X86-32]
2049 Maximal number of shapers.
2051 show_msr= [x86] show boot-time MSR settings
2052 Format: { <integer> }
2053 Show boot-time (BIOS-initialized) MSR settings.
2054 The parameter means the number of CPUs to show,
2055 for example 1 means boot CPU only.
2058 See header of drivers/scsi/sim710.c.
2065 slub_debug[=options[,slabs]] [MM, SLUB]
2066 Enabling slub_debug allows one to determine the
2067 culprit if slab objects become corrupted. Enabling
2068 slub_debug can create guard zones around objects and
2069 may poison objects when not in use. Also tracks the
2070 last alloc / free. For more information see
2071 Documentation/vm/slub.txt.
2073 slub_max_order= [MM, SLUB]
2074 Determines the maximum allowed order for slabs.
2075 A high setting may cause OOMs due to memory
2076 fragmentation. For more information see
2077 Documentation/vm/slub.txt.
2079 slub_min_objects= [MM, SLUB]
2080 The minimum number of objects per slab. SLUB will
2081 increase the slab order up to slub_max_order to
2082 generate a sufficiently large slab able to contain
2083 the number of objects indicated. The higher the number
2084 of objects the smaller the overhead of tracking slabs
2085 and the less frequently locks need to be acquired.
2086 For more information see Documentation/vm/slub.txt.
2088 slub_min_order= [MM, SLUB]
2089 Determines the mininum page order for slabs. Must be
2090 lower than slub_max_order.
2091 For more information see Documentation/vm/slub.txt.
2093 slub_nomerge [MM, SLUB]
2094 Disable merging of slabs with similar size. May be
2095 necessary if there is some reason to distinguish
2096 allocs to different slabs. Debug options disable
2097 merging on their own.
2098 For more information see Documentation/vm/slub.txt.
2101 Format: <io1>[,<io2>[,...,<io8>]]
2103 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2104 attempt to substitute SMP alternatives once at boot.
2106 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2107 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2108 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2109 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2110 smsc-ircc2.ircc_irq= [HW] IRQ line
2111 smsc-ircc2.ircc_dma= [HW] DMA channel
2112 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2113 0: Toshiba Satellite 1800 (GP data pin select)
2114 1: Fast pin select (default)
2117 snd-ad1816a= [HW,ALSA]
2119 snd-ad1848= [HW,ALSA]
2121 snd-ali5451= [HW,ALSA]
2123 snd-als100= [HW,ALSA]
2125 snd-als4000= [HW,ALSA]
2127 snd-azt2320= [HW,ALSA]
2129 snd-cmi8330= [HW,ALSA]
2131 snd-cmipci= [HW,ALSA]
2133 snd-cs4231= [HW,ALSA]
2135 snd-cs4232= [HW,ALSA]
2137 snd-cs4236= [HW,ALSA]
2139 snd-cs4281= [HW,ALSA]
2141 snd-cs46xx= [HW,ALSA]
2143 snd-dt019x= [HW,ALSA]
2145 snd-dummy= [HW,ALSA]
2147 snd-emu10k1= [HW,ALSA]
2149 snd-ens1370= [HW,ALSA]
2151 snd-ens1371= [HW,ALSA]
2153 snd-es968= [HW,ALSA]
2155 snd-es1688= [HW,ALSA]
2157 snd-es18xx= [HW,ALSA]
2159 snd-es1938= [HW,ALSA]
2161 snd-es1968= [HW,ALSA]
2163 snd-fm801= [HW,ALSA]
2165 snd-gusclassic= [HW,ALSA]
2167 snd-gusextreme= [HW,ALSA]
2169 snd-gusmax= [HW,ALSA]
2173 snd-ice1712= [HW,ALSA]
2175 snd-intel8x0= [HW,ALSA]
2177 snd-interwave= [HW,ALSA]
2182 snd-korg1212= [HW,ALSA]
2184 snd-maestro3= [HW,ALSA]
2186 snd-mpu401= [HW,ALSA]
2188 snd-mtpav= [HW,ALSA]
2190 snd-nm256= [HW,ALSA]
2192 snd-opl3sa2= [HW,ALSA]
2200 snd-opti93x= [HW,ALSA]
2204 snd-rme32= [HW,ALSA]
2206 snd-rme96= [HW,ALSA]
2208 snd-rme9652= [HW,ALSA]
2214 snd-sbawe= [HW,ALSA]
2216 snd-serial= [HW,ALSA]
2218 snd-sgalaxy= [HW,ALSA]
2220 snd-sonicvibes= [HW,ALSA]
2225 snd-sun-cs4231= [HW,ALSA]
2227 snd-trident= [HW,ALSA]
2229 snd-usb-audio= [HW,ALSA,USB]
2231 snd-via82xx= [HW,ALSA]
2233 snd-virmidi= [HW,ALSA]
2235 snd-wavefront= [HW,ALSA]
2237 snd-ymfpci= [HW,ALSA]
2240 [KNL] Should the soft-lockup detector generate panics.
2242 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2243 See Documentation/sonypi.txt
2245 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2246 See Documentation/serial/specialix.txt.
2248 spia_io_base= [HW,MTD]
2254 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2256 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2257 See Documentation/scsi/st.txt.
2260 Enabled the stack tracer on boot up.
2264 Set the STI (builtin display/keyboard on the HP-PARISC
2265 machines) console (graphic card) which should be used
2266 as the initial boot-console.
2267 See also comment in drivers/video/console/sticore.c.
2270 See comment in drivers/video/console/sticore.c.
2273 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2277 Control how the NFS server code allocates CPUs to
2278 service thread pools. Depending on how many NICs
2279 you have and where their interrupts are bound, this
2280 option will affect which CPUs will do NFS serving.
2281 Note: this parameter cannot be changed while the
2282 NFS server is running.
2284 auto the server chooses an appropriate mode
2285 automatically using heuristics
2286 global a single global pool contains all CPUs
2287 percpu one pool for each CPU
2288 pernode one pool for each NUMA node (equivalent
2289 to global on non-NUMA machines)
2291 swiotlb= [IA-64] Number of I/O TLB slabs
2295 sym53c416= [HW,SCSI]
2296 See header of drivers/scsi/sym53c416.c.
2298 sysrq_always_enabled
2300 Ignore sysrq setting - this boot parameter will
2301 neutralize any effect of /proc/sys/kernel/sysrq.
2302 Useful for debugging.
2305 See header of drivers/scsi/t128.c.
2309 test_suspend= [SUSPEND]
2310 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2311 standby suspend) as the system sleep state to briefly
2312 enter during system startup. The system is woken from
2313 this state using a wakeup-capable RTC alarm.
2315 thash_entries= [KNL,NET]
2316 Set number of hash buckets for TCP connection
2318 thermal.act= [HW,ACPI]
2319 -1: disable all active trip points in all thermal zones
2320 <degrees C>: override all lowest active trip points
2322 thermal.crt= [HW,ACPI]
2323 -1: disable all critical trip points in all thermal zones
2324 <degrees C>: override all critical trip points
2326 thermal.nocrt= [HW,ACPI]
2327 Set to disable actions on ACPI thermal zone
2328 critical and hot trip points.
2330 thermal.off= [HW,ACPI]
2331 1: disable ACPI thermal control
2333 thermal.psv= [HW,ACPI]
2334 -1: disable all passive trip points
2335 <degrees C>: override all passive trip points to this
2338 thermal.tzp= [HW,ACPI]
2339 Specify global default ACPI thermal zone polling rate
2340 <deci-seconds>: poll all this frequency
2341 0: no polling (default)
2344 See comment before function dc390_setup() in
2345 drivers/scsi/tmscsim.c.
2349 Specify if the kernel should make use of the cpu
2350 topology informations if the hardware supports these.
2351 The scheduler will make use of these informations and
2352 e.g. base its process migration decisions on it.
2357 trix= [HW,OSS] MediaTrix AudioTrix Pro
2359 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2361 tsc= Disable clocksource-must-verify flag for TSC.
2363 [x86] reliable: mark tsc clocksource as reliable, this
2364 disables clocksource verification at runtime.
2365 Used to enable high-resolution timer mode on older
2366 hardware, and in virtualized environment.
2368 turbografx.map[2|3]= [HW,JOY]
2369 TurboGraFX parallel port interface
2371 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2372 See also Documentation/input/joystick-parport.txt
2374 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2375 See header of drivers/scsi/u14-34f.c.
2384 [USB] Ignore overcurrent events (default N).
2385 Some badly-designed motherboards generate lots of
2386 bogus events, for ports that aren't wired to
2387 anything. Set this parameter to avoid log spamming.
2388 Note that genuine overcurrent events won't be
2393 Set unknown_nmi_panic=1 early on boot.
2395 usbcore.autosuspend=
2396 [USB] The autosuspend time delay (in seconds) used
2397 for newly-detected USB devices (default 2). This
2398 is the time required before an idle device will be
2399 autosuspended. Devices for which the delay is set
2400 to a negative value won't be autosuspended at all.
2402 usbcore.usbfs_snoop=
2403 [USB] Set to log all usbfs traffic (default 0 = off).
2405 usbcore.blinkenlights=
2406 [USB] Set to cycle leds on hubs (default 0 = off).
2408 usbcore.old_scheme_first=
2409 [USB] Start with the old device initialization
2410 scheme (default 0 = off).
2412 usbcore.use_both_schemes=
2413 [USB] Try the other device initialization scheme
2414 if the first one fails (default 1 = enabled).
2416 usbcore.initial_descriptor_timeout=
2417 [USB] Specifies timeout for the initial 64-byte
2418 USB_REQ_GET_DESCRIPTOR request in milliseconds
2419 (default 5000 = 5.0 seconds).
2422 [USBHID] The interval which mice are to be polled at.
2424 usb-storage.delay_use=
2425 [UMS] The delay in seconds before a new device is
2426 scanned for Logical Units (default 5).
2429 [UMS] A list of quirks entries to supplement or
2430 override the built-in unusual_devs list. List
2431 entries are separated by commas. Each entry has
2432 the form VID:PID:Flags where VID and PID are Vendor
2433 and Product ID values (4-digit hex numbers) and
2434 Flags is a set of characters, each corresponding
2435 to a common usb-storage quirk flag as follows:
2436 a = SANE_SENSE (collect more than 18 bytes
2438 c = FIX_CAPACITY (decrease the reported
2439 device capacity by one sector);
2440 h = CAPACITY_HEURISTICS (decrease the
2441 reported device capacity by one
2442 sector if the number is odd);
2443 i = IGNORE_DEVICE (don't bind to this
2445 l = NOT_LOCKABLE (don't try to lock and
2446 unlock ejectable media);
2447 m = MAX_SECTORS_64 (don't transfer more
2448 than 64 sectors = 32 KB at a time);
2449 o = CAPACITY_OK (accept the capacity
2450 reported by the device);
2451 r = IGNORE_RESIDUE (the device reports
2452 bogus residue values);
2453 s = SINGLE_LUN (the device has only one
2455 w = NO_WP_DETECT (don't test whether the
2456 medium is write-protected).
2457 Example: quirks=0419:aaf5:rl,0421:0433:rc
2459 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2460 kernel's map of available physical RAM.
2462 vdso= [X86-32,SH,x86-64]
2463 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2464 vdso=1: enable VDSO (default)
2465 vdso=0: disable VDSO mapping
2467 vdso32= [X86-32,X86-64]
2468 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2469 vdso32=1: enable 32-bit VDSO (default)
2470 vdso32=0: disable 32-bit VDSO mapping
2473 vector=percpu: enable percpu vector domain
2475 video= [FB] Frame buffer configuration
2476 See Documentation/fb/modedb.txt.
2478 vga= [BOOT,X86-32] Select a particular video mode
2479 See Documentation/x86/boot.txt and
2480 Documentation/svga.txt.
2481 Use vga=ask for menu.
2482 This is actually a boot loader parameter; the value is
2483 passed to the kernel using a special protocol.
2485 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2486 size of <nn>. This can be used to increase the
2487 minimum size (128MB on x86). It can also be used to
2488 decrease the size and leave more room for directly
2491 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2494 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2497 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2500 waveartist= [HW,OSS]
2501 Format: <io>,<irq>,<dma>,<dma2>
2504 See header of drivers/scsi/wd33c93.c.
2507 See header of drivers/scsi/wd7000.c.
2510 See Documentation/watchdog/wdt.txt.
2512 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2513 xd_geo= See header of drivers/block/xd.c.
2515 xirc2ps_cs= [NET,PCMCIA]
2517 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2519 norandmaps Don't use address space randomization. Equivalent to
2520 echo 0 > /proc/sys/kernel/randomize_va_space
2522 ______________________________________________________________________
2526 Add documentation for ALSA options.
2527 Add more DRM drivers.